The study will systematically explore the efficacy of EMG biofeedback and operant shaping in overcoming spasticity and related neuromuscular deficits in victims of stroke, accidental brain injury, or cerebral palsy. Subjects will be spastic hemiplegics devoid of other medical or behavioral problems which might interfere with learning. Spastic muscles will be trained in synergist pairs. Each subject will be trained to relax normal and then spastic muscles under quiet resting conditions. He will then be trained to extend control of spasticity to gradually more challenging stimulus and task conditions. In experiment I, the spastic limb remains at rest while "overflow" conditions such as distracting noise or use of the normal contralateral limb are introduced. In experiment II, the subject strives to relax the spastic muscles during passive stretch at increasing isokinetic rates. In experiment III neuromuscular skills prerequisite to active synergistic use of the spastic limb are trained. Each experiment involves individualized training over several daily sessions, allowing subjects to proceed at their own rates in mastering successively more difficult tasks. An on-line computer quantifies and records momentary EMG levels, generates visual feedback displays, carries out response shaping and reinforcement schedules, and processes data concurrently.